Even as the Senate voted unanimously Tuesday to begin debate on the measure creating the new Cabinet agency, which could take two or three weeks, Republicans and Democrats dug in their heels over the contentious personnel issues.

Senate Majority Leader Tom Daschle called Mr. Bush's proposal "a power grab of unprecedented magnitude" that would undermine the nonpolitical government civil service system and threaten labor union rights and protections for one-third of the workers.

"We're not going to roll over when it comes to principles and beliefs we hold to be very, very important," said Daschle, D-S.D.

Tom Ridge, the president's point man on homeland security, insisted the new department needs broader powers to hire, fire, promote or demote and pay employees — and waive union rights in matters of national security — to meet emerging terrorist threats.

"The president has indicated it's not just a matter of reconfiguring letterheads and addresses," Ridge told reporters after meeting privately with Republican senators.

In an appearance on CBS' "The Early Show," Ridge said "if you limit the ability of the president to move people around within this organization, you will not have done everything you can to protect this country and our way of life."

The Senate GOP leader, Trent Lott of Mississippi, predicted Mr. Bush would bring enough political pressure to bear to get much of what he wants in the end.

"It's about doing the job," Lott said.

The president met Tuesday with GOP senators at the White House to reinforce his demands for the new Cabinet agency and planned similar sessions later this week with Democrats. Later in the day, however, the White House issued a statement that Mr. Bush would veto the Senate bill in its current form.

In addition to the personnel issues, the statement said Mr. Bush objects to the bill's "intrusive" new White House Homeland Security Office with a Senate-confirmed director.

Presidential power to waive union collective bargaining rights for federal employees for national security reasons has existed since 1977, said Sen. Fred Thompson, R-Tenn. Congress has approved more flexible personnel systems for agencies such as the Internal Revenue Service, the Department of Housing and Urban Development, the Federal Aviation Administration and the new Transportation Security Administration.

Even though there was no immediate sign of compromise on the personnel dispute, both sides predicted the Senate would pass a Homeland Security bill later this month. That would set up negotiations on a final version with the House, which in July approved a measure much like Mr. Bush's original plan.

Both bills would merge all or parts of 22 agencies into a single department focused on protecting Americans against terrorism at home. The Coast Guard, Transportation Security Administration, Customs Service, Border Patrol, Secret Service and Federal Emergency Management Agency are among those to be moved.

Both measures would also set up a new intelligence analysis office — the Senate's version is more powerful — that would sift through data produced by the CIA, FBI and others to identify potential threats and take action to protect targets or prevent terrorist acts.

The chief Senate sponsor, Democrat Joseph Lieberman of Connecticut, said the areas of agreement were too important to let the legislation founder over the worker issues.

"There is an enormous agreement here on what I would say are the guts of this bill," Lieberman said.

The threat of extended delay, or filibuster, evaporated Tuesday when Sen. Robert Byrd, D-W.Va., announced he would support bringing the legislation to the floor. Byrd had resisted immediate consideration of the House-passed bill in July, arguing that such a massive reorganization plan deserved more deliberate scrutiny.

Other difficult issues to be debated would:

Exempt private industry from the Freedom of Information Act in some cases.

Delay by one year the deadline for airports to begin screening all checked baggage for explosives.

Allow the president to shift money around within the new department without congressional approval.